Lift 3.0 + Omniauth 0.8

Updating omniauth 0.8 so it can be used with Lift 3.0 also.
Google sign up

Adding google provider to allow sign up/in using google+
Google sign up

Removing the case class to parse the Json response.
Linkedin sign up

Adding linkedin provider to allow sign up/in using linkedin.
Merge pull request #28 from ggarciajr/master

Linkedin and Google Providers